Remove an unused struct element

Also simplify an if/else into just an if as suggested by golint.

producer.go

@@ -139,7 +139,6 @@ type MessageToSend struct {
 	Key, Value Encoder
 
 	// these are filled in by the producer as the message is processed
-	broker    *Broker
 	offset    int64
 	partition int32
 	flags     flagSet
@@ -312,7 +311,7 @@ func (p *Producer) leaderDispatcher(topic string, partition int32, input chan *M
 			if backlog == nil {
 				// on the very first retried message we send off a chaser so that we know when everything "in between" has made it
 				// back to us and we can safely flush the backlog (otherwise we risk re-ordering messages)
-				output <- &MessageToSend{Topic: topic, partition: partition, broker: leader, flags: chaser}
+				output <- &MessageToSend{Topic: topic, partition: partition, flags: chaser}
 				Logger.Println("Producer dispatching retried messages to new leader.")
 				backlog = make([]*MessageToSend, 0)
 				p.unrefBrokerWorker(leader)
@@ -340,7 +339,6 @@ func (p *Producer) leaderDispatcher(topic string, partition int32, input chan *M
 			}
 
 			for _, msg := range backlog {
-				msg.broker = leader
 				output <- msg
 			}
 			Logger.Println("Producer backlog processsed.")
@@ -368,7 +366,6 @@ func (p *Producer) leaderDispatcher(topic string, partition int32, input chan *M
 			output = p.getBrokerWorker(leader)
 		}
 
-		msg.broker = leader
 		output <- msg
 	}
 
@@ -659,9 +656,8 @@ func (p *Producer) buildRequest(batch map[string]map[int32][]*MessageToSend) *Pr
 
 	if empty {
 		return nil
-	} else {
-		return req
 	}
+	return req
 }
 
 func (p *Producer) returnMessages(batch []*MessageToSend, err error) {